A noninvasive fluorescence imaging-based platform measures 3D anisotropic extracellular diffusion

Diffusion is a major molecular transport mechanism in biological systems. Quantifying direction-dependent (i.e., anisotropic) diffusion is vitally important to depicting how the three-dimensional (3D) tissue structure and composition affect the biochemical environment, and thus define tissue functions. However, a tool for noninvasively measuring the 3D anisotropic extracellular diffusion of biorelevant molecules is not yet available. Here, we present light-sheet imaging-based Fourier transform fluorescence recovery after photobleaching (LiFT-FRAP), which noninvasively determines 3D diffusion tensors of various biomolecules with diffusivities up to 51 mu m(2) s(-1), reaching the physiological diffusivity range in most biological systems. Using cornea as an example, LiFT-FRAP reveals fundamental limitations of current invasive two-dimensional diffusion measurements, which have drawn controversial conclusions on extracellular diffusion in healthy and clinically treated tissues. Moreover, LiFT-FRAP demonstrates that tissue structural or compositional changes caused by diseases or scaffold fabrication yield direction-dependent diffusion changes. These results demonstrate LiFT-FRAP as a powerful platform technology for studying disease mechanisms, advancing clinical outcomes, and improving tissue engineering. It is challenging to quantify anisotropic diffusion in biological systems. Here the authors report light-sheet imaging-based Fourier transform fluorescence recovery after photobleaching (LiFT-FRAP) to noninvasively determine 3D diffusion tensors of various biomolecules at physiological diffusivity.

Automated summary

The researchers introduce a noninvasive method, LiFT-FRAP, for determining 3D diffusion tensors of various biomolecules at physiological diffusivity, providing insights into direction-dependent diffusion changes in tissues caused by diseases or scaffold fabrication.